Ekpyrotic cosmology resurfaces

A six-year-old controversial theory that told of a time before the Big Bang is undergoing a resurgence, only to be lampooned again by its original critics.

The theory of ekpyrotic cosmology was first put forward as an alternative to the standard “inflation” model of the universe. Inflation supposes that just after the Big Bang the universe underwent a brief period of rapid expansion. This amplified tiny density perturbations, which evolved into the stars, galaxies and galaxy clusters we see today. Although there is currently no way to prove that inflation ever occurred, the fact that it provides such a simple explanation for cosmic structure and the flatness of the universe has cemented it in cosmological doctrine since it was outlined in the early 1980s.

In ekpyrotic cosmology — which was proposed in 2001 by physicists Paul Steinhardt, Justin Khoury, Neil Turok and Burt Ovrut — there is no beginning of time. Instead, our visible universe exists on one of two four-dimensional “branes” floating in a five-dimensional space. These two branes are locked in an endless oscillatory motion in which they creep together, “bounce” through each other, withdraw and then creep together again (see animation: Branes collide). At each bounce, which is like a fresh Big Bang, ripples in the branes collide and liberate energy at different places to produce the initial density perturbations. And because energy conservation would favour a flat brane, the theory explains why our visible universe is flat too. “It’s like the antichrist to inflation,” says Khoury.

Past critics of ekpyrotic cosmology, however, have highlighted two particular problems. First, every bounce would be a point of infinite temperature and pressure known as a singularity, which is impossible to describe using conventional physics. Second, it was not clear that the density perturbations would be present on all length scales, as observations of the primordial radiation left over from the Big Bang — that is, the cosmic microwave background — indicate they should be.

'From A to Z'

It’s like the antichrist to inflation
Justin Khoury, Perimeter Institute

Now, Khoury and Evgeny Buchbinder, who are currently at the Perimeter Institute in Waterloo, Canada, with Ovrut, who is at the University of Pennsylvania in the US, say they have overcome these problems. Building on work performed in 2006 by Leonardo Senatore, Paolo Creminelli and others, the researchers say they can bring density perturbations “unscathed” through a bounce while leaving them scale-invariant on the other side. “For the first time we’re able to track the story from A to Z,” says Khoury.

Physicists have managed to get around the sharp bounce singularity in the past, but not without generating undesirable negative-energy particles. By merging ekpyrotic cosmology with a scalar field known as a ghost condensate, Khoury’s group claim to suffer no such complications. This field, which manifests as a fluid of massless particles in the same quantum state that permeate space with repulsive gravity, can smooth out the bounce.

On its own, though, a ghost condensate cannot keep the density perturbations scale-invariant. To do this, Khoury’s team invoke another scalar field. It turns out that the difference between the entropy fluctuations in this field and those the ghost-condensate field yields unambiguously scale-invariant perturbations (Phys. Rev. D76 123503).

Stiff opposition

These ideas are barking up the wrong tree
Nima Arkani-Hamed, Harvard University

The original criticisms of ekpyrotic cosmology were spearheaded by Andrei Linde of Stanford University in the US, and he has little praise for “new ekpyrotic cosmology” either. He claims that the theory is still plagued by negative-energy particles, which lead to a “catastrophic” instability in the early universe’s vacuum (arXiv:0712.2040v2). “The universe described by this theory instantly dies,” he told physicsworld.com. “Therefore it does not even come close to describing our world.”

Khoury insists that Linde’s argument is wrong because he does not acknowledge that particle physics theories are effective, in that they only ever work over a finite range of energy scales. “He’s predicting something by trusting the theory beyond the point where it should be trusted,” explains Khoury. “By contrast, at all times in our description of the bounce, the universe is at a sufficiently low energy that we can trust the ghost condensate description.”

Nima Arkani-Hamed of Harvard University, who first formulated the theory of ghost condensates, sides with Khoury’s group. Nevertheless, he thinks that new ekpyrotic cosmology is too complicated to rival inflation, and admits that he has “poked fun” at Senatore and Creminelli — his former post-docs — for their attempts to tackle the theory. “I believe these ideas are barking up the wrong tree,” he told physicsworld.com. “But they are definitely worth working with, they are interesting and clever.”

Brane-World Imitations

All those “brane-world solutions” are but inconsistent mechanistic imitations of the unreduced complex-dynamic cosmology framework that has been developed and presented for many years, before brane-world imitations (e.g. arxiv.org…9902015 , arxiv.org…9902016 , see also arxiv.org…0510240 for a recent review). The difference is that complex-dynamic cosmology (or “quantum field mechanics”, arxiv.org…0401164 , arxiv.org…0601140 ) provides explicit, natural, no-postulate structure emergence in the process of unreduced, “minimally structured” interaction between two physically real “proto-fields/media”, instead of unlimited number of “postulates” about reality, its structures and laws, expressed in terms of purely abstract, only mathematical, physically empty (and therefore inevitably inconsistent) guesses in officially imposed approaches. In the unreduced complex-dynamic cosmology, the observed universe, its basic entities (space, time, matter, forces), their properties (mass, charge,...) and laws of behaviour (quantum, classical and relativistic features, complexity and “thermodynamics”/randomness,...) emerge all together, without any ruptures and contradictions (e.g. between “quantum”, “classical”, and “relativistic” features in usual schemes, “branes” including). One obtains thus not only mathematically but also physically complete, realistic, directly observable and “tangible” universe structure and behaviour patterns, up to any their desirable detail.

Nevertheless, all the huge efforts, investment in and attention to fundamental science (super-expensive “experimental verification” including) go exclusively to increasingly, now surrealistically inconsistent and broken, but always “officially accepted” schemes. It's something strangely resembling the antichrist epoch description, indeed... A characteristic piece of such peculiar “logic” of scholar science operation is rather well illustrated at the end of the above article by a directly involved “professional” opinion: “I believe these ideas are barking up the wrong tree,” he told physicsworld.com. “But they are definitely worth working with, they are interesting and clever.” Well, and after revealing such a “solid” basis of the whole official science machinery, hasn't physicsworld.com or anything else able to think in this human world any further questions about such a way of doing and supporting science? Especially taking into account the existence of consistent, causally derived and unifying solution free from artificially inserted abstractions, “dark matters” and “hidden dimensions”...

Brane collision by Aether Wave Theory

Quote:

Originally posted by anomaly256

..animation doesn't do very much to illustrate the concept. It just seems.. ...

..unphysical? By Aether Wave Theory the Universe is formed by interior of giant dense blob of Aether, i.e. collapsar or giant dense star, similar to black hole, whose interior is undergoing the phase transition, similar to condensation of supersaturated solution (superstruny.aspweb.c…naac1.gif).

During this process the material of collapsar will condense in few nested stages, which are induced by collisions of spherical zones ("foam branes"), originated from previous generation of Universe. At the place of head-to-head collisions the giant dense droplets of metastable matter in the form of quasars ("white holes") will appear. By evaporate cooling these quasars will lose part of their matter, which will condense into surrounding galaxies and the resulting central black hole will remain. The structure of spherical membranes can be detected as the dark matter streaks (superstruny.aspweb.c…collapse.gif). By another word, the formation of Universe has occurred by the same way, like the phase transitions inside of core of supernova or similar situations. The resulting structure is related to root vector system of Lie E8 group ("mirror hall" composed of nested dodecahedrons).

that are continually colliding and separating

Well, we can observe such process at the very beginning of supercritical vapor condensation, where the density fluctuations are forming a less or more flat artifacts ("branes"), which are colliding each other. At the place of collision the more dense phase of Aether will condense in the chain of nested phase transitions (which will proceed by the same way).

So more realistic animation of expyrotic cosmology could appear something like this one: superstruny.aspweb.c…dynafoam.gif It's evident, the authors of Ekpyrotic cosmology have guessed it correctly, but they didn't noticed it inertial nature. A quite common problem of cosmology from the Ptolemy's times, indeed. Note that the branes are just density fluctuation of Aether, deformed by the optics of energy spreading inside of foamy environment into flat shapes, i.e. by the same way, like the spongy density fluctuations inside of condensing vapor.

alternative ...“inflation” model

IMO, ekpyrotic cosmology isn't an alternative of inflation cosmology - rather the calibration of former one. We should realize, during collision of branes the phase transition has occurred at the same "moment", which can be perceived as "fast" expansion of space from the internal observer perspective, like the slowing of energy spreading inside of condensing vapor, where two shock waves collide (so called the Wilson cloud).

By such way, both theories can play well together and everybody can remain happy...;-) But such model will reverse the paradigm of matter formation inside of our Universe: the substantial portion of matter has evaporated from white holes, instead of collapse into dark ones. It means, just the quasars can become the primary form of matter inside of our Universe - not these sparse clouds supposedly formed during inflation. And such process even continues, so we can observe it! Such concept agrees well with the latest observations of active galactic nuclei and other indicia.

new ekpyrotic cosmology is too complicated

I suppose, the ekpyrotic cosmology can be reconciled with inflationary theory by much easier and intuitive way and the resulting model can be even tested by observations (the evaporative formation of matter near quasars is noticeable effect and it leads to the spherical shape of young gallaxies).

If nothing else, I cannot imagine the interpretation of "ghost condensate" by AWT - albeit this doesn't mean, such interpretation is impossible, indeed. Even quite crazy theories can give often deeper sense from some particular perspective.